scholarly journals A ribosome-inactivating protein in a Drosophila defensive symbiont

2015 ◽  
Vol 113 (2) ◽  
pp. 350-355 ◽  
Author(s):  
Phineas T. Hamilton ◽  
Fangni Peng ◽  
Martin J. Boulanger ◽  
Steve J. Perlman
Keyword(s):  
Ribosomal Rna ◽  
28S Rrna ◽  
Ribosome Inactivating Protein ◽  
Defensive Symbiosis ◽  
Rapid Spread ◽  
A Cell ◽  
Underlying Mechanisms ◽  
Dependent Modification ◽  
Dependent Mechanism

Vertically transmitted symbionts that protect their hosts against parasites and pathogens are well known from insects, yet the underlying mechanisms of symbiont-mediated defense are largely unclear. A striking example of an ecologically important defensive symbiosis involves the woodland fly Drosophila neotestacea, which is protected by the bacterial endosymbiont Spiroplasma when parasitized by the nematode Howardula aoronymphium. The benefit of this defense strategy has led to the rapid spread of Spiroplasma throughout the range of D. neotestacea, although the molecular basis for this protection has been unresolved. Here, we show that Spiroplasma encodes a ribosome-inactivating protein (RIP) related to Shiga-like toxins from enterohemorrhagic Escherichia coli and that Howardula ribosomal RNA (rRNA) is depurinated during Spiroplasma-mediated protection of D. neotestacea. First, we show that recombinant Spiroplasma RIP catalyzes depurination of 28S rRNAs in a cell-free assay, as well as Howardula rRNA in vitro at the canonical RIP target site within the α-sarcin/ricin loop (SRL) of 28S rRNA. We then show that Howardula parasites in Spiroplasma-infected flies show a strong signal of rRNA depurination consistent with RIP-dependent modification and large decreases in the proportion of 28S rRNA intact at the α-sarcin/ricin loop. Notably, host 28S rRNA is largely unaffected, suggesting targeted specificity. Collectively, our study identifies a novel RIP in an insect defensive symbiont and suggests an underlying RIP-dependent mechanism in Spiroplasma-mediated defense.

scholarly journals Regulation of cilia abundance in multiciliated cells

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Rashmi Nanjundappa ◽  
Dong Kong ◽  
Kyuhwan Shim ◽  
Tim Stearns ◽  
Steven L Brody ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Surface Area ◽  
Ex Vivo ◽  
Compensatory Mechanism ◽  
Multiciliated Cells ◽  
Culture Model ◽  
A Cell ◽  
Dependent Mechanism

Multiciliated cells (MCC) contain hundreds of motile cilia used to propel fluid over their surface. To template these cilia, each MCC produces between 100-600 centrioles by a process termed centriole amplification. Yet, how MCC regulate the precise number of centrioles and cilia remains unknown. Airway progenitor cells contain two parental centrioles (PC) and form structures called deuterosomes that nucleate centrioles during amplification. Using an ex vivo airway culture model, we show that ablation of PC does not perturb deuterosome formation and centriole amplification. In contrast, loss of PC caused an increase in deuterosome and centriole abundance, highlighting the presence of a compensatory mechanism. Quantification of centriole abundance in vitro and in vivo identified a linear relationship between surface area and centriole number. By manipulating cell size, we discovered that centriole number scales with surface area. Our results demonstrate that a cell-intrinsic surface area-dependent mechanism controls centriole and cilia abundance in multiciliated cells.

Eukaryotic Ribosome Assembly

2019 ◽  
Vol 88 (1) ◽  
pp. 281-306 ◽  
Author(s):  
Jochen Baßler ◽  
Ed Hurt
Keyword(s):  
Ribosomal Rna ◽  
Nuclear Export ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Cryo Electron Microscopy ◽  
A Cell ◽  
Cellular Pathways ◽  
Nucleolar Rnas ◽  
Shed Light

Ribosomes, which synthesize the proteins of a cell, comprise ribosomal RNA and ribosomal proteins, which coassemble hierarchically during a process termed ribosome biogenesis. Historically, biochemical and molecular biology approaches have revealed how preribosomal particles form and mature in consecutive steps, starting in the nucleolus and terminating after nuclear export into the cytoplasm. However, only recently, due to the revolution in cryo–electron microscopy, could pseudoatomic structures of different preribosomal particles be obtained. Together with in vitro maturation assays, these findings shed light on how nascent ribosomes progress stepwise along a dynamic biogenesis pathway. Preribosomes assemble gradually, chaperoned by a myriad of assembly factors and small nucleolar RNAs, before they reach maturity and enter translation. This information will lead to a better understanding of how ribosome synthesis is linked to other cellular pathways in humans and how it can cause diseases, including cancer, if disturbed.

scholarly journals The Traditional Medicinal Plants Cuphea calophylla, Tibouchina kingii, and Pseudelephantopus spiralis Attenuate Inflammatory and Oxidative Mediators

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Ana María Ramírez-Atehortúa ◽  
Lorena Morales-Agudelo ◽  
Edison Osorio ◽  
Oscar J. Lara-Guzmán
Keyword(s):  
Antioxidant Activities ◽  
Free System ◽  
Oxidative Markers ◽  
Aerial Parts ◽  
Traditional Medicinal Plants ◽  
A Cell ◽  
Anti Inflammatory ◽  
Underlying Mechanisms ◽  
Cox 1

Aerial parts of Cuphea calophylla, Tibouchina kingii, and Pseudelephantopus spiralis have been used in Colombian traditional medicine for inflammation. However, the underlying mechanisms that could explain the anti-inflammatory actions remain unknown. This study aimed to elucidate the anti-inflammatory and cytoprotective effects of hydroalcoholic extracts from C. calophylla (HECC), T. kingii (HETK), and P. spiralis (HEPS) in LPS-stimulated THP-1 macrophages. Reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA) were monitored as inflammatory and oxidative markers. The inhibition of lipoxygenase (LOX) and cyclooxygenase (COX) activities in a cell-free system were also investigated. Antioxidant activities were determined using standard in vitro methods. All extracts inhibited the NO, ROS, and MDA levels. HETK showed the highest ROS production inhibition and the highest antioxidant values, whereas HETK and HEPS significantly decreased the cytotoxicity mediated by LPS. The release of MDA was reduced significantly by all extracts. Moreover, the catalytic activity of LOX was inhibited by HECC and HETK. HECC was a more potent reducer of COX-2 activity. All extracts effectively suppressed COX-1 activity. In summary, these results suggest that HECC, HEPS, and HETK possess anti-inflammatory properties. Therefore, these plants could provide a valuable source of natural bioactive compounds for the treatment of inflammatory-related diseases.

Estrogen reduces myogenic tone through a nitric oxide-dependent mechanism in rat cerebral arteries

1998 ◽  
Vol 275 (1) ◽  
pp. H292-H300 ◽  
Author(s):  
Greg G. Geary ◽  
Diana N. Krause ◽  
Sue P. Duckles
Keyword(s):  
Nitric Oxide ◽  
Cerebral Arteries ◽  
Myogenic Tone ◽  
No Production ◽  
Luminal Diameter ◽  
Underlying Mechanisms ◽  
Synthase Inhibitor ◽  
Endothelial Nitric Oxide ◽  
Dependent Mechanism

Gender differences in the incidence of stroke and migraine appear to be related to circulating levels of estrogen; however, the underlying mechanisms are not yet understood. Using resistance-sized arteries pressurized in vitro, we have found that myogenic tone of rat cerebral arteries differs between males and females. This difference appears to result from estrogen enhancement of endothelial nitric oxide (NO) production. Luminal diameter was measured in middle cerebral artery segments from males and from females that were either untreated, ovariectomized (Ovx), or ovariectomized with estrogen replacement (Ovx + Est). The maximal passive diameters (0 Ca2++ 1 mM EDTA) of arteries from all four groups were identical. In response to a series of 10-mmHg step increases in transmural pressure (20–80 mmHg), myogenic tone was greater and vascular distensibility less in arteries from males and Ovx females compared with arteries from either untreated or Ovx + Est females. In the presence of N G-nitro-l-arginine methyl ester (l-NAME; 1 μM), an NO synthase inhibitor, myogenic tone was increased in all arteries, but the differences among arteries from the various groups were abolished. Addition ofl-arginine (1 mM) in the presence of l-NAME restored the differences in myogenic tone, suggesting that estrogen works through an NO-dependent mechanism in cerebral arteries. To determine the target of NO-dependent modulation of myogenic tone, we used tetraethylammonium (TEA; 1 mM) to inhibit large-conductance, calcium-activated K+(BKCa) channels. In the presence of TEA, the myogenic tone of arteries from all groups increased significantly; however, myogenic tone in arteries from males and Ovx females remained significantly greater than in arteries from either untreated or Ovx + Est females. This suggests that activity of BKCa channels influences myogenic tone but does not directly mediate the effects of estrogen. Estrogen appears to alter myogenic tone by increasing cerebrovascular NO production and/or action.

scholarly journals Persistent Mycobacterium tuberculosis infection in mice requires PerM for successful cell division

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Ruojun Wang ◽  
Kaj Kreutzfeldt ◽  
Helene Botella ◽  
Julien Vaubourgeix ◽  
Dirk Schnappinger ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cell Division ◽  
Acute Infection ◽  
Chronic Phase ◽  
Integral Membrane Protein ◽  
Cell Replication ◽  
Mycobacterium Tuberculosis Infection ◽  
A Cell ◽  
Underlying Mechanisms

The ability of Mycobacterium tuberculosis (Mtb) to persist in its host is central to the pathogenesis of tuberculosis, yet the underlying mechanisms remain incompletely defined. PerM, an integral membrane protein, is required for persistence of Mtb in mice. Here, we show that perM deletion caused a cell division defect specifically during the chronic phase of mouse infection, but did not affect Mtb’s cell replication during acute infection. We further demonstrate that PerM is required for cell division in chronically infected mice and in vitro under host-relevant stresses because it is part of the mycobacterial divisome and stabilizes the essential divisome protein FtsB. These data highlight the importance of sustained cell division for Mtb persistence, define condition-specific requirements for cell division and reveal that survival of Mtb during chronic infection depends on a persistence divisome.

scholarly journals Regulation of Cilia Abundance in Multiciliated Cells

2018 ◽  
Author(s):  
Rashmi Nanjundappa ◽  
Dong Kong ◽  
Kyuhwan Shim ◽  
Tim Stearns ◽  
Steven L. Brody ◽  
...  
Keyword(s):  
Surface Area ◽  
Direct Relationship ◽  
Ex Vivo ◽  
Multiciliated Cells ◽  
Culture Model ◽  
A Cell ◽  
Total Complement ◽  
Dependent Mechanism

AbstractMulticiliated cells (MCC) are specialized epithelia that contain hundreds of motile cilia used to propel fluid over the surface of the cell. To template these cilia, each MCC produces hundreds of centrioles by a process termed centriole amplification. Airway progenitor cells initially contain two parental centrioles that nucleate multiple centrioles at once, and structures called deuterosomes that assemble the vast majority of centrioles during amplification. Remarkably, how each cell regulates the precise number of its centrioles and cilia remains unknown. Here, we investigate mechanisms that establish centriole number in MCC using an ex vivo airway culture model. We show that ablation of parental centrioles, via inhibition of Plk4 kinase, does not perturb deuterosome formation and centriole amplification, nor alter the total complement of centrioles per cell. Airway MCC vary in size and surface area, and exhibit a broad range in centriole number. Quantification of centriole abundance in vitro and in vivo identified a direct relationship between cell-surface area and centriole number. By manipulating cell size and shape, we discovered that centriole number scales with increasing surface area. Collectively, our results demonstrate that parental centrioles and Plk4 are dispensable for deuterosome formation, centriole amplification, and establishment of centriole number. Instead, a cell-intrinsic surface area-dependent mechanism controls centriole and cilia abundance in multiciliated cells.

scholarly journals A Simplified Method for Quantifying Cell Migration/Wound Healing in 96-Well Plates

2010 ◽  
Vol 15 (4) ◽  
pp. 427-433 ◽  
Author(s):  
Patrick Y. K. Yue ◽  
Emily P. Y. Leung ◽  
N. K. Mak ◽  
Ricky N. S. Wong
Keyword(s):  
Cell Migration ◽  
Umbilical Vein ◽  
Cell Monolayer ◽  
Migration Assay ◽  
Migration Study ◽  
A Cell ◽  
Multiple Sample ◽  
Underlying Mechanisms ◽  
Umbilical Vein Endothelial Cells

Cell migration plays a key role in both normal physiological and pathological conditions. The study of cell migration and its underlying mechanisms is of great significance in various fields of research, including basic biology and pharmaceutical development. The cell migration or scratch wounding assay is an easy and economical in vitro method that allows researchers to assess a large number of testing compounds. Even though this simple assay has been used for decades, researchers are still trying to modify such experimental protocols and wounding devices. In this study, an 8-channel mechanical “wounder” was designed for performing a cell migration assay, particularly in a 96-well culture plate format. With special designs of a guiding bar and adjustable pins for use with disposable pipette tips, this wounder confined the scratch area within the center of each well to ensure a perfect contact between the pins and the well surface. As a result, this mechanical wounder produces a uniform denudation of a cell monolayer in a 96-well plate with a wound size of around 600 µm. Using this improved wounding device, the effects of epidermal growth factor and DL-α-difluoromethylornithine on the reepithelialization of rat intestinal epithelial cells (IEC-6) and serum on the wound recovery of human umbilical vein endothelial cells were demonstrated. This wounder facilitates cell migration study and can be applicable for multiple sample analysis.

scholarly journals Effect of aspirin on tumour cell colony formation and evolution

2017 ◽  
Vol 14 (134) ◽  
pp. 20170374 ◽  
Author(s):  
Dominik Wodarz ◽  
Ajay Goel ◽  
C. Richard Boland ◽  
Natalia L. Komarova
Keyword(s):  
Cell Lines ◽  
Cell Population ◽  
Tumour Cell ◽  
Evolutionary Potential ◽  
A Cell ◽  
Tumour Cell Lines ◽  
Underlying Mechanisms ◽  
Cell Colony

Aspirin is known to reduce the risk of colorectal cancer (CRC) incidence, but the underlying mechanisms are not fully understood. In a previous study, we quantified the in vitro growth kinetics of different CRC tumour cell lines treated with varying doses of aspirin, measuring the rate of cell division and cell death. Here, we use these measured parameters to calculate the chances of successful clonal expansion and to determine the evolutionary potential of the tumour cell lines in the presence and absence of aspirin. The calculations indicate that aspirin increases the probability that a single tumour cell fails to clonally expand. Further, calculations suggest that aspirin increases the evolutionary potential of an expanding tumour cell colony. An aspirin-treated tumour cell population is predicted to result in the accumulation of more mutations (and is thus more virulent and more difficult to treat) than a cell population of the same size that grew without aspirin. This indicates a potential trade-off between delaying the onset of cancer and increasing its evolutionary potential through chemoprevention. Further work needs to investigate to what extent these findings apply to in vivo settings, and to what degree they contribute to the epidemiologically documented aspirin-mediated protection.

scholarly journals THE SYNTHESIS OF 5S RNA AND ITS RELATIONSHIP TO 18S AND 28S RIBOSOMAL RNA IN THE BOBBED MUTANTS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1975 ◽  
Vol 81 (4) ◽  
pp. 723-738
Author(s):  
Jag Mohan
Keyword(s):  
Drosophila Melanogaster ◽  
Ribosomal Rna ◽  
In Vivo Studies ◽  
28S Rrna ◽  
5S Rna ◽  
Rna Molecules ◽  
Molar Ratios ◽  
Rna Genes

ABSTRACT Ribosomes contain one molecule each of 5S, 18S and 28S RNA. In Drosophila melanogaster although the genes for 18S+28S are physically separated from the 5S RNA genes, the multiplicity of various ribosomal RNA genes is roughly the same. Thus a coordinate synthesis of these three molecules might seem feasible. This problem has been approached by determining the molar ratios of various RNA's in ovaries and in adult flies. In ovaries there is a slight excess of 5S RNA molecules over other rRNA's, but in adult flies no such differences exist. Bobbed mutants also have the same molar ratios as wild-type flies. Results on 5S RNA synthesis in both in vitro and in vivo studies show that it is reduced in coordination with 18S+28S rRNA in the bobbed mutants of Drosophila melanogaster. Various possibilities are discussed in considering the implications of these results.

scholarly journals Gut bacteria-derived 5-hydroxyindole is a potent stimulant of intestinal motility via its action on L-type calcium channels

PLoS Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. e3001070
Author(s):  
Barbora Waclawiková ◽  
Amber Bullock ◽  
Markus Schwalbe ◽  
Carmen Aranzamendi ◽  
Sieger A. Nelemans ◽  
...  
Keyword(s):  
Calcium Channels ◽  
Gut Bacteria ◽  
Bioactive Molecules ◽  
Interindividual Variation ◽  
Microbial Conversion ◽  
Targeted Interventions ◽  
Intestinal Physiology ◽  
A Cell ◽  
Underlying Mechanisms

Microbial conversion of dietary or drug substrates into small bioactive molecules represents a regulatory mechanism by which the gut microbiota alters intestinal physiology. Here, we show that a wide variety of gut bacteria can metabolize the dietary supplement and antidepressant 5-hydroxytryptophan (5-HTP) to 5-hydroxyindole (5-HI) via the tryptophanase (TnaA) enzyme. Oral administration of 5-HTP results in detection of 5-HI in fecal samples of healthy volunteers with interindividual variation. The production of 5-HI is inhibited upon pH reduction in in vitro studies. When administered orally in rats, 5-HI significantly accelerates the total gut transit time (TGTT). Deciphering the underlying mechanisms of action reveals that 5-HI accelerates gut contractility via activation of L-type calcium channels located on the colonic smooth muscle cells. Moreover, 5-HI stimulation of a cell line model of intestinal enterochromaffin cells results in significant increase in serotonin production. Together, our findings support a role for bacterial metabolism in altering gut motility and lay the foundation for microbiota-targeted interventions.

Sign in / Sign up

Export Citation Format

Share Document